This invention relates to multifilament polyester yarns and particularly to improved multifilament polyethylene terephthalate yarns for industrial uses. More particuarly, it relates to an improved multifilament polyethylene terephthalate yarn and a new fiber finishing process for polyethylene terephthalate yarns. Still more particularly, it relates to a fiber finish composition designed specifically for subsequent tire cord processing for polyethylene terephthalate yarns, and the eventual production of pneumatic passenger car tires.
The prior art is replete with fiber finish compositions, some of which are quite specific in composition and relate to specific types of fibers. Small changes in a given fiber finish composition or in its application during a fiber-manufacturing process can and frequently do result in tremendous improvements in both processing and end use of the fiber.
Polyester industrial yarn finishes generally comprise a combination of a lubricant, an antistat, and several emulsifiers. For example, U.S. Pat. No. 3,672,977 to K. C. Dardoufas, discloses an improved polyester industrial yarn which is produced by first treating the yarn with a spin finish comprising hexadecyl stearate, refined coconut oil, ethoxylated tallow amine, ethoxylated lauryl alcohol, sodium salt of alkylarylsulfonate, dinonyl-sodium-sulfosuccinate, 4,4'-thio-bis-(3-methyl-6-tertbutylphenol) and white mineral oil, and then treating the yarn with an overfinish comprising glycerol monooleate, decaglycerol tetraoleate, ethoxylated tall oil fatty acids, sulfated glycerol trioleate, ethoxylated tallow amine and hexadecyl stearate.
Following its production by either the above-described process or some other process, the polyester yarn may undergo further processing or treatment depending on the desired end use. For example, in the production of tire cord, polyester yarn is normally plied, then twisted, and treated with one or two dips. Dip treatment has as one of its objectives acceptable adhesion of the cord and rubber in the ultimate product, e.g., pneumatic tires. High temperatures are usually employed in the curing of each dip treatment. Unfortunately, the yarn finish or overfinish of U.S. Pat. No. 3,672,977 is based on volatile lubricants which burn off or fume at the temperatures required to cure the dip treatment or treatments. Similar results obtain from other high temperature treatment of the yarn. This emission of fumes, naturally, is of great concern to industry due to the associated health and environmental problems--a subject of governmental regulation of the past few years.
With this framework in mind, research was undertaken to produce a yarn finish or overfinish which would significantly reduce emissions. This has been accomplished by the present invention. Surprisingly, however, not only were emissions reduced, but the additional benefit of increased adhesion, to be discussed later, was obtained.
The closest prior art known to the inventors is U.S. Pat. No. 4,069,160, which discloses an improved, low fuming, thermally stable, texturing finish for a synthetic filamentary material, comprising a lubricant, an emulsifier, an antistat-auxiliary emulsifier, and optionally, a thermal stabilizer.
This patent, however, does not teach the present invention, which will be more clearly understood upon reference to the description and examples which follow.